Seeing Is Believing

To the Editors:

Henry Petroski’s Engineering column “The Evolution of Eyeglasses” (September–October) is characteristically informative. Petroski suggests that we do not know why centuries passed between the invention of eyeglasses and the invention of telescopes and microscopes. Vasco Ronchi provided a clear and persuasive explanation in his 1970 book The Nature of Light. He noted 13th-century scholars’ “emphatic and unanimous” rejection of the idea that glass lenses could have any consequences for science. Ronchi explains that glass lenses were qualitatively incompatible with ancient Greek theories of optics, which, strange as it may seem, were still predominant in the late Middle Ages. It took almost three centuries for the visible facts of lenses to overcome this entrenched theoretical bias. A closely related discussion is provided in a paper I recently published in Ecological Psychology.

A particularly vivid depiction of the early use of (and fears about) eyeglasses can be found in The Name of the Rose, Umberto Eco’s novel of early 14th-century monastic murder and intrigue. Eco’s protagonist, William of Baskerville, owns a pair of spectacles, knows when they were invented, and confesses that he often refrains from wearing them in public, fearing that they (and, by implication, he) might be thought diabolical.